One important characteristic of an ink for ink-jet recording is good ozone resistance. This means to prevent discoloration (degradation of image quality) of printed matter by ink-jet recording attributable to contact with the ozone in air. Copper phthalocyanine dyes, which often are used as colorants for cyan colored inks, have good light fastness as compared with dyes typically used for magenta and yellow colors. However, many copper phthalocyanine dyes have inadequate ozone resistance. Some copper phthalocyanine pigments have been developed which have good light fastness as well as ozone resistance.
In ink for ink jet recording, an anticorrosive agent such as a benzotriazole compound is added to prevent corrosion of metallic materials that are brought into contact with the ink in the ink passage of ink-jet head. However, when an anticorrosive agent such as a benzotriazole compound is added to ink having a copper phthalocyanine pigment as a colorant, precipitates are created.